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Auteur Basso, Daniela
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Titre : Calcareous algae in changing environments Type de document : texte imprimé Auteurs : Basso, Daniela, Auteur Importance : pp. 05-11 Format : 24 cm. Langues : Anglais (eng) Index. décimale : 550 Sciences de la terre Résumé : Although calcareous algae are known both in present environments and fossil records, from shelf and upper slope settings, either in warm seas for green algae or at all latitudes for red algae, we still need models to quantify their abundance in space and time. Calcareous algae are an important component of biogenic carbonate production but they are very sensitive to marine acidification and rise in temperature, as illustrated by the effects of ongoing global change. Contributions herein were first presented at the 6th Regional (European) Symposium of the International "Fossil Algae" Association: they include two reviews respectively devoted to the carbonate production of red and green algae, and a suite of investigations covering quantification, facies delineation, and controlling factors spanning the present-day Mediterranean Sea and Eastern Pacific going back to the Jurassic of Romania. Calcareous algae in changing environments [texte imprimé] / Basso, Daniela, Auteur . - [s.d.] . - pp. 05-11 ; 24 cm.
Langues : Anglais (eng)
Index. décimale : 550 Sciences de la terre Résumé : Although calcareous algae are known both in present environments and fossil records, from shelf and upper slope settings, either in warm seas for green algae or at all latitudes for red algae, we still need models to quantify their abundance in space and time. Calcareous algae are an important component of biogenic carbonate production but they are very sensitive to marine acidification and rise in temperature, as illustrated by the effects of ongoing global change. Contributions herein were first presented at the 6th Regional (European) Symposium of the International "Fossil Algae" Association: they include two reviews respectively devoted to the carbonate production of red and green algae, and a suite of investigations covering quantification, facies delineation, and controlling factors spanning the present-day Mediterranean Sea and Eastern Pacific going back to the Jurassic of Romania. Exemplaires(0)
Disponibilité aucun exemplaire
Titre : Carbonate production by calcareous red algae and global change Type de document : texte imprimé Auteurs : Basso, Daniela, Auteur Importance : pp. 13-33 Format : 24 cm. Langues : Anglais (eng) Index. décimale : 550 Sciences de la terre Résumé : The most important groups of modern red calcareous algae are the Mg-calcite secreting Corallinales and Sporolithales, and the aragonitic Peyssonneliales and Nemaliales. They are common on the world's shelves and are vulnerable to the global warming and the lowering of pH of sea water, caused by the ongoing increase in anthropogenic CO2. Among them, coralline algae are ecosystem engineers and major producers of carbonate sediment, of particular importance in temperate and cold seas. Corallines respond to marine acidification and rising temperature showing decreased net calcification, decreased growth and reproduction, as well as reduced abundance and diversity, leading to death and ecological shift to dominant non-calcifying algae. Despite their key ecological and sedimentological role, and because of their vulnerability to marine warming and acidification, our knowledge of the distribution of coralline-dominated habitats and the quantification of their carbonate production is not adequate to allow proper environmental management and confident modelling of a global carbon budget. Locating the algal carbonate factories around the world, then describing them, e.g., evaluating their extent and their production, are a priority for future research. Carbonate production by calcareous red algae and global change [texte imprimé] / Basso, Daniela, Auteur . - [s.d.] . - pp. 13-33 ; 24 cm.
Langues : Anglais (eng)
Index. décimale : 550 Sciences de la terre Résumé : The most important groups of modern red calcareous algae are the Mg-calcite secreting Corallinales and Sporolithales, and the aragonitic Peyssonneliales and Nemaliales. They are common on the world's shelves and are vulnerable to the global warming and the lowering of pH of sea water, caused by the ongoing increase in anthropogenic CO2. Among them, coralline algae are ecosystem engineers and major producers of carbonate sediment, of particular importance in temperate and cold seas. Corallines respond to marine acidification and rising temperature showing decreased net calcification, decreased growth and reproduction, as well as reduced abundance and diversity, leading to death and ecological shift to dominant non-calcifying algae. Despite their key ecological and sedimentological role, and because of their vulnerability to marine warming and acidification, our knowledge of the distribution of coralline-dominated habitats and the quantification of their carbonate production is not adequate to allow proper environmental management and confident modelling of a global carbon budget. Locating the algal carbonate factories around the world, then describing them, e.g., evaluating their extent and their production, are a priority for future research. Exemplaires(0)
Disponibilité aucun exemplaire Quantification of the coralline carbonate from a Serravallian rhodolith bed of the Tertiary Piedmont Basin (Stazzano, Alessandria, NW Italy) / Basso, Daniela
Titre : Quantification of the coralline carbonate from a Serravallian rhodolith bed of the Tertiary Piedmont Basin (Stazzano, Alessandria, NW Italy) Type de document : texte imprimé Auteurs : Basso, Daniela, Auteur Importance : pp. 137-149 Format : 24 cm. Langues : Anglais (eng) Index. décimale : 550 Sciences de la terre Résumé : Digital photographs of the surface of Serravallian rhodolith-bearing strata from Stazzano (Tertiary Piedmont Basin) Italy have been elaborated by Image-J open-source software (U.S. National Institutes of Health - NIH), to obtain a map of the algal surface in each photograph. The 33 images in the 7 m-thick outcrop, covering a total of 11.53 m2, were complemented by data on rhodolith shape, structure, composition and taphonomy. The Serravallian rhodolith body was produced in a long-lasting infralittoral sedimentary environment and then transported into deeper water by slumping. Although biological and geological definitions of rhodolith-dominated facies are inconsistent in some respects, the image analysis described here allows direct comparison of percentages of rhodolith dominance in discrete fossil rhodolith facies and their living counterparts. The procedures involved are both rapid and inexpensive, so the method appears very useful for carbonate quantification. The calculated algal cover, based only on rhodoliths > 2 cm, ranges from 11.9 to 59.7% (mean 27.3%). The carbonate production rate of the Serravallian rhodolith bed was probably in the range 55 to 136.3 g CaCO3 m-2 yr' as calculated for a Brazilian present-day analogue. Quantification of the coralline carbonate from a Serravallian rhodolith bed of the Tertiary Piedmont Basin (Stazzano, Alessandria, NW Italy) [texte imprimé] / Basso, Daniela, Auteur . - [s.d.] . - pp. 137-149 ; 24 cm.
Langues : Anglais (eng)
Index. décimale : 550 Sciences de la terre Résumé : Digital photographs of the surface of Serravallian rhodolith-bearing strata from Stazzano (Tertiary Piedmont Basin) Italy have been elaborated by Image-J open-source software (U.S. National Institutes of Health - NIH), to obtain a map of the algal surface in each photograph. The 33 images in the 7 m-thick outcrop, covering a total of 11.53 m2, were complemented by data on rhodolith shape, structure, composition and taphonomy. The Serravallian rhodolith body was produced in a long-lasting infralittoral sedimentary environment and then transported into deeper water by slumping. Although biological and geological definitions of rhodolith-dominated facies are inconsistent in some respects, the image analysis described here allows direct comparison of percentages of rhodolith dominance in discrete fossil rhodolith facies and their living counterparts. The procedures involved are both rapid and inexpensive, so the method appears very useful for carbonate quantification. The calculated algal cover, based only on rhodoliths > 2 cm, ranges from 11.9 to 59.7% (mean 27.3%). The carbonate production rate of the Serravallian rhodolith bed was probably in the range 55 to 136.3 g CaCO3 m-2 yr' as calculated for a Brazilian present-day analogue. Exemplaires(0)
Disponibilité aucun exemplaire
Titre : The contribution of calcareous algae to the biogenic carbonates of the continental shelf : Pontian Islands, Tyrrhenian Sea, Italy Type de document : texte imprimé Auteurs : Basso, Daniela, Auteur Importance : pp. 61-76 Format : 24 cm. Langues : Anglais (eng) Index. décimale : 550 Sciences de la terre Résumé : This contribution discusses current carbonate deposition in the channel between the Ponza and Palmarola islands and along the western coast of Palmarola, focusing on the quantitative contribution of biogenic carbonate and in particular on the production and accumulation of carbonates by coralline algae. Seventeen out of 150 grab samples have been selected as representative of the main sedimentary features facies of the seafloor between 30 and 100 m of water depth (wd). They were analyzed using XRD and EDTA titration. Thin sections of the same samples were made to identify their biogenic components and to quantify the contribution of calcareous algae to the total sediment. Maximum carbonate production takes place between 40 and 70 m wd, with the percentage of carbonates ranging between 83.1 and 95.7%. of the total. Multidimensional statistical analyses found two different carbonate facies: the coralline algae facies (CA) occupies 38 km2 between 30 and 70 m wd, and the carbonate matrix facies (CM) covers 24 km2 between 70 and 100 m wd. An estimate of the current contribution of algal carbonates to seafloor sediments is about 80% in the CA facies and 15% in the CM facies. The accumulation of total carbonate sediments in the uppermost 2 cm interval of the CA facies is calculated to be 20 566 g nv2 and the fraction of coralline carbonate in the superficial 2-cm layer of the CM facies is calculated as 16452 g nr2. The production rate of the mean 7% live coralline covers ranges between 7.91 and 31.64 g m"2 yr1. The contribution of calcareous algae to the biogenic carbonates of the continental shelf : Pontian Islands, Tyrrhenian Sea, Italy [texte imprimé] / Basso, Daniela, Auteur . - [s.d.] . - pp. 61-76 ; 24 cm.
Langues : Anglais (eng)
Index. décimale : 550 Sciences de la terre Résumé : This contribution discusses current carbonate deposition in the channel between the Ponza and Palmarola islands and along the western coast of Palmarola, focusing on the quantitative contribution of biogenic carbonate and in particular on the production and accumulation of carbonates by coralline algae. Seventeen out of 150 grab samples have been selected as representative of the main sedimentary features facies of the seafloor between 30 and 100 m of water depth (wd). They were analyzed using XRD and EDTA titration. Thin sections of the same samples were made to identify their biogenic components and to quantify the contribution of calcareous algae to the total sediment. Maximum carbonate production takes place between 40 and 70 m wd, with the percentage of carbonates ranging between 83.1 and 95.7%. of the total. Multidimensional statistical analyses found two different carbonate facies: the coralline algae facies (CA) occupies 38 km2 between 30 and 70 m wd, and the carbonate matrix facies (CM) covers 24 km2 between 70 and 100 m wd. An estimate of the current contribution of algal carbonates to seafloor sediments is about 80% in the CA facies and 15% in the CM facies. The accumulation of total carbonate sediments in the uppermost 2 cm interval of the CA facies is calculated to be 20 566 g nv2 and the fraction of coralline carbonate in the superficial 2-cm layer of the CM facies is calculated as 16452 g nr2. The production rate of the mean 7% live coralline covers ranges between 7.91 and 31.64 g m"2 yr1. Exemplaires(0)
Disponibilité aucun exemplaire
